Many operating systems use two independently operated actuators to perform equally important, but opposite, functions. As an example, in a hydrostatic transmission for driving a track-type vehicle, two independent foot treadles are provided for stearing the vehicle, one treadle controlling the speed of one track and the second treadle controlling the speed of the other track. When either treadle is in the fully depressed condition, the track controlled by that treadle will reverse for a maximum steer position or a spot turn.
It is undesirable for both treadles to be fully depressed at the same time for this would not steer the vehicle, but instead would result in the direction of drive of the vehicle being reversed.
The present invention is directed to overcoming one or more of the problems as set forth above.